Three dimensional (3D) stereoscopic image display technology has become the dominant trend in the field of image display technology. The principle of the three dimensional stereoscopic imaging is using the left eye and right eye images having parallax to constitute a stereoscopic image with depth-of-field vision. In the current market, the 3D animations and games have included space information as designed, such that the space information can be utilized to be transformed into depth information easily. To generate a 3D stereoscopic image, it is used that gray level values of a 2D image are generally valued from 0 to 255 which represent the nearest image portion to the farthest one, and a depth map is establish which the size of the depth map is completely same as the corresponding 2D image, thereby a 3D stereoscopic image can be generated.
Traditionally, the method for generating a depth map can be divided to manual method, automatic method and semi-automatic method. The depth value is determined manually in the manual method. In the semi-automatic method, the objects are first selected manually, and then the approximate depth value information is calculated by an object tracking algorithm. In the automatic method, the depth map is generated by animation software, for example 3DS Max or Maya, or is calculated from two different pictures with different angles of view. For instance, in order to generate the depth map manually by using tool software such as Photoshop, follow these steps:
1. Establish eye points;
2. Analyze how many 3D objects should be divided;
3. Define the gray level values;
4. Select or divide 3D objects;
5. Use Polygon Lasso Tools and Linear Gradient to make gray level maps of other 3D objects;
6. Use a layer with gray level value 000 as a background of these 3D objects;
7. Obtain the depth map and save the depth map as the uncompressed BMP image format.
The current transformation technology for CG animation or video usually utilizes the automatic method to generate the depth value information because the generated depth information is more accurate. In the prior technology, the calculated depth map is transformed into the depth information to generate images at different viewing angles, however, the prior technology does not consider that the conventionally generated depth map may result in the relative distances among different objects being very small, i.e. the colors of the objects are very similar and the contrast is low. Therefore, the stereoscopic effect may not be so pronounced or the details of the images cannot be shown more clearly.
Moreover, when the depth information of the 2D depth map overly concentrates in certain region, i.e. the gray level values of the depth map are distributed unevenly, the foreground may be overly fused with the background, and the stereoscopic perception thereof will be poor. This situation often happens in the depth maps generated by using the semi-automatic method or the automatic method. If the shortcomings that the depth values overly concentrate on certain region can be improved, the 3D stereoscopic effect becomes manifest.
Therefore, there is still a need for a technical solution for solving the aforementioned problems of the conventional depth map.